WASHINGTON – U.S. President Barack Obama travels to the Paris climate summit on Sunday for what could be the crowning diplomatic achievement of his presidency, yet one that climate experts say will still leave the planet on a path toward dangerous levels of global warming.

Obama has spent more than a year laying the foundation for the summit, coaxing leaders from the major developing countries and elsewhere to make unprecedented pledges to limit greenhouse-gas emissions, protect forests and undertake formidable new renewable energy projects.

Now, despite the recent terrorist attacks on Paris, he will join French President François Hollande in pressing world leaders for further commitments to help seal the text of a formal deal while resisting demands, especially from countries most vulnerable to the effects of global warming, for the United States and other historically large emitters to do even more.

“This is an existential issue for humanity, and his leadership will be appreciated and rewarded by history,” Nigel Purvis – founding president of Climate Advisers, a District of Columbia-based consultancy, and a former State Department treaty lawyer – said of the president.

In many ways, the Paris summit — known formally as the 21st U.N. Conference of the Parties, or COP21 — is already a success. More than 160 countries have put forward climate action plans, and eight of the largest of those economies have pledged collectively to double their renewable energy supply by 2030, according to the World Resources Institute.

Brazil will become the first major developing country to reduce its absolute greenhouse-gas emissions, in contrast to countries that simply reduce the carbon intensity of their economies. And China, the world’s largest emitter, is standing by its pledge to put a ceiling on greenhouse-gas production, introduce a nationwide cap and trade program and give green energy preference on its grid. Obama will meet Chinese President Xi Jinping on Monday morning.

In addition, at a time when Congress has been reluctant to approve the $3 billion the president has requested for the international Green Climate Fund, the Obama administration is striving to spur private-sector investment in new technologies to fight climate change.

On Monday afternoon in Paris, Bill Gates and about 20 other wealthy business people will unveil a multibillion-dollar plan for research to improve the technology available for fighting climate change, an event Obama plans to attend and showcase. A former U.S. government official on climate issues said the Microsoft co-founder and Obama would vow to find ways to protect the climate without diverting resources from poverty alleviation.

In June, Gates told the Financial Times that over the next five years he would double to $2 billion of his personal wealth invested in innovative green technologies to “bend the curve” on climate change. The other wealthy investors are expected to add considerably to that sum.

Gates has insisted that his pledge be linked to higher government research spending and about a dozen major countries will likely announce a doubling of their research and development spending, according to people familiar with the talks.

Without a breakthrough in technology or major additional cuts in emissions, there is “virtually no chance” that global temperatures will stay below the international target of 2 degrees Celsius (3.6 degrees Fahrenheit), according to a new paper in the journal Science.

Meanwhile, many stumbling blocks remain for climate negotiators in Paris.

At the Copenhagen summit, wealthy countries agreed to spend $100 billion a year by 2020 from both public and private sources to help developing countries combat climate change. So far, according to the Organization for Economic Cooperation and Development, pledges from wealthy countries only amount to about $62 billion a year.

A group of island countries most directly threatened by rising sea levels will meet with Obama on Tuesday morning, seeking damage payments from developed countries that historically spewed most of the global warming gases. U.S. negotiators are strongly opposed to anything that smacks of reparations, but might propose a way to subsidize insurance premiums for vulnerable areas, according to people familiar with the talks.

India is sprearheading related challenges. It has already pledged to slash the amount of greenhouse gas emitted for every unit of economic output by about a third, and to sharply boost the amount of renewable energy it uses. But with a fast-growing economy and goals to hook up the 240 million people still without any electricity, India will contribute more to global energy demand than any other country over the next 25 years, the International Energy Agency said Friday. The IEA’s executive director Fatih Birol said “India’s energy transformation requires three things: investment, investment and investment.”

India has demanded that wealthier countries provide more direct aid and financial assistance to cover the cost of technology transfer for its climate efforts.

“We are geared up for the battle ahead in Paris, and I want to make it clear that India would not be bullied into accepting the position of the developed countries,” the Minister of Environment, Forests and Climate Change Prakash Javadekar told the IANS news service in an interview. Javadekar called the 2009 Copenhagen climate summit “Floppenhagen.”

Arvind Panagariya, an economics professor at Columbia University and vice chairman of the National Institution for Transforming India, said in a blog post that climate negotiators should use the “Polluter Pay Principle, which says that the costs of clean up of pollution must be borne by those who cause it.” He noted that India’s share of historical emissions was just 2.8 percent, and of current emissions just 5.7 percent.

Many countries have followed India’s example, making parts of their climate action plans contingent on international financial assistance. Indonesia, for example, has pledged to cut emissions by about 28 percent on its own by 2030 but says it could cut by 41 percent with international support.

Many American environmental groups also want the developed world to do more. Purvis said that the emissions reductions from Brazil’s actions on the forest sector alone is greater than all of Europe’s emissions reductions. Environmental and business groups will host scores of side events during the conference.

Still, U.S. negotiators believe they have accomplished a lot.

“Climate negotiations are inherently difficult,” a senior climate negotiator at the State Department said in an interview in July. “There are 190 plus countries and managing climate change affects managing one’s entire economy. There are countries in all different positions.” He said “countries act in groups and blocs and we have to get a consensus.”

But he said that “what’s important is that countries take action as ambitious as they’re able to do.” Whereas the Kyoto Protocol asked little from developing countries, developing countries are now among the world’s largest emitters and must make efforts of their own. The climate plans filed in October in anticipation of the Paris conference largely met that goal, he said.

Obama has also traveled his own road to the Paris summit. As a state legislator from Illinois, he sought to ease strains on southern Illinois coal producers by advocating federal subsidies for liquefying coal. In his first inaugural address he made only passing reference to a warming planet.

But as president, he has taken a series of major steps. With the economy in turmoil, he convinced ailing auto companies to back tougher fuel efficiency standards. He turned a portion of the economic stimulus bill in 2009 into the largest clean energy bill ever. And he has introduced the Clean Power Plan to limit greenhouse-gas emissions from industrial and power plants. At the same time, he has supported shale gas drilling and offshore oil exploration.

He appears to have had no “eureka moment” over climate change, but simply seems to have absorbed the widening scientific consensus, say people who have worked for him.

“We will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations,” he said in his second inaugural address. “Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires and crippling drought and more powerful storms.”

He continued, “The path towards sustainable energy sources will be long and sometimes difficult. But America cannot resist this transition, we must lead it.”

David Sandalow, a fellow at Columbia University’s Center for Global Energy Policy and a former senior official at the Energy Department and National Security Council, said that Obama deserved credit for combining real policy with the presidency’s bully pulpit.

“Global warming is almost a uniquely challenging policy problem,” he said. “It’s a problem caused by invisible gases and proceeds at a pace that terrifies scientists but can be difficult for people to see in their ordinary lives. And President Obama has recognized the importance of both speaking to the American public about this issue and pursuing policies to address it.”